Question

Can someone explain oxidation values to me?

Answer 1

source: http://www.ausetute.com.au/oxistate.html

Answer 2

Can you help me with an equation?

Answer 3

Sure, I hope I can

Answer 4

Mg+2HCl = MgCl2+H2

Answer 5

why is there a subscript 2 at the end? 1 know it has to due with oxidation values...

Answer 6

1. What is the oxidation number of Mg?

Answer 7

+2

Answer 8

Every neutral molecule/compound has total oxidation number of 0 (neutral), therefore to lack of 2 electrons in Mg must be neutralised by ?

Answer 9

The addition of two?

Answer 10

they would have to be negative though

Answer 11

yes :D

Answer 12

The oxidation number of each Cl would be?

Answer 13

-1 ?

Answer 14

yes, Cl is in group 7, it needs one more electron to reach octet number.the two additional electron that Mg need to release in order to reach octet number would be the electron that Cl needed to reach the octet number

Answer 15

subscript 2 means the molecule contains 2Cl and 1 Mg. It states the number of molecule needed to make a molecule or ion compound

Answer 16

It states the number of atoms needed to make a molecule or ion compound

Answer 17

oh, so would Hydrogen be -1?

Answer 18

+1 (group 1) release an electron to reach octet number

Answer 19

oh so the oxidation values have to be equal to each other on both sides of the equation?

Answer 20

the oxidation values can increase or decrease, for example in your equation Mg at first has 0 oxidation values then it has +2 oxidation values.For every molecules that are not ionic, the total oxidation number must be zero.

Answer 21

which molecules are ionic?

Answer 22

wait, but the oxidation values have to equal 0.

Answer 23

so if you add both sides of the equation it has to equal 0 or just one side?

Answer 24

ionic is the one that has superscript in it and +/- sign

Answer 25

each molecule has to be zero

Answer 26

so yeah, both sides has to be equal to zero

Answer 27

but then the left side equals 2 and the right equals -2

Answer 28

whats the difference between a big 2 on the right side of the H and a subscript 2 on the left?

Answer 29

2HCl means that there is 2 HCl (2 mole of HCl) , MgCl2 means that there is 1 Mg and 2 Cl

Answer 30

so why is 2H wrong and H2 isnt?

Answer 31

because H2 is two H with covalent bond

Answer 32

they have bonding, while 2H is 2 separate H

Answer 33

H2 oxidation number is zero, so does Mg. As long as it has no superscript, it always have the total of oxidation number/values : 0

Answer 34

Oxidation states tutorial
http://openstudy.com/updates/53c24e3ee4b05c273e9c66c5

Answer 35

Really sorry I can't continue to reply, must turn off the computer, sorry ):

Answer 36

okay thanks for all the help!

Answer 37

good job @colouringme :)

Answer 38

@bloofoffiction i hope the tutorial helps you, if there is something unclear, ask, i will clear out the doubt :D

Answer 39

I'm still not sure how the energy levels come into play. @Somy

Answer 40

I doing corrections on a lab. My original equation was Mg+2HCl -> MgCl2+2H

Answer 41

The correct one is Mg+2HCl -> MgCl2+H2

Answer 42

I'm supposed to explain why mine is wrong and explain the logic behind the correct one.

Answer 43

ohh i see

Answer 44

so your question is
why H2 and not 2H

Answer 45

If I don't finish three pages of this by tomorrow I end with a B in the class

Answer 46

did i get you?

Answer 47

yup

Answer 48

He wants me to explain why using oxidation values

Answer 49

mmmm alright let me think how to explain so it makes sense

Answer 50

okay thanks

Answer 51

\(\sf Mg+2HCl -> MgCl_2+2H\)

\(\sf Mg+2HCl -> MgCl_2+H_2\)

well firstly \(\sf H\) doesn't exist alone like that, it exists as \(\sf H_2\)
now the reason is that its unstable alone
as i've mentioned of octet rule
for H, maximum number of electrons required to reach stability is 2
originally H has only 1 electron on its outer shell, so it needs one more electron
so 2 H atoms share their electrons by forming a covalent bond and, thus, making a stable \(\sf H_2 \) molecule,
in other words H only exists in molecule form, as \(\sf H_2\)

Answer 52

the reaction if you want to look at oxidation states
then pay attention to this
\(\sf Mg^0 + 2H^+ +2Cl^- → Mg^{2+} + 2Cl^- + 2H^{+}\)
look at the ions
Mg is originally 0 at charge
HCl = overall charge is also 0
so we need overall charges 0 on the other side too
now Mg makes a bond with Cl
Mg gives 2 electrons to 2 Cls
Cl originally needs 1 electron, since it already has 7, so one more & it'll reach octet state
BUT
Mg needs to give 2 electrons to reach octet
thus it requires to Cl atoms

now overall charge at that case will be 0

now when H was in compound state with Cl = HCl
when the compound breaks, 2 ions form
\(\sf Cl^-\) ion and \(\sf H^+\) ion
now lets imagine the reaction is not balanced yet, in other words it looks like this-
\(\sf Mg + HCl → MgCl_2 + H \)
lets just imagine
- we solved the issue with Mg wanting 2 Cls
thats why now we need to balance
meaning make it so we have 2Cl atoms on the left side
\(\sf Mg + 2HCl → MgCl_2 + H \)
so now after balancing this
we have 2 H atoms on the left side
BUT
these will not be a 0 charged atoms,
2 coefficient near HCl indicates that there are 2 of HCls
in other words, each will have to break
and you will end up with free radicals
those are unstable atoms
that have electrons that participated in a bond
but their energy level is high once they break out from the bond, thus, they are highly unstable and want to react with something as quickly as it can

Answer 53

so, the target for Cl free radicals are Mg since it has 2 electrons to give
and since there will be 2 free H radicals left
they will just form a bond between each other - covalent bond
and reach their stable state

remember: in chemistry, all chemicals, atoms or whatever that is, always wants to reach its stable state
since hydrogen was left out from the compound, and since there were 2 of them
they just made a bond to reach stability

Answer 54

you wrote it as \(\sf 2H \)
which shows that you are saying that there are 2 free radicals of H
but its impossible for them to stay like that
again, because they are unstable
thus they desire to make a bond between each other and become a molecule

Answer 55

ah ok

Answer 56

does it explain all you wanted to know?

Answer 57

yes

Answer 58

thats good then :)